Such a vessel is known from US-A-2006/0260191. In FIG. 4 of this publication a gasification reactor is shown for gasification of a solid carbonaceous feedstock to obtain a synthesis gas mixture having a temperature of between 1200 and 1800° C. The reactor has an outlet for hot synthesis gas at its upper end and an outlet for slag at its lower end. The reactor itself is provided with a quenching means to lower the temperature in a first step to a temperature below the solidification point of the non-gaseous components as present in the synthesis gas. The synthesis gas is further reduced in temperature by injecting a mist of water into the flow of synthesis gas in a separate quenching vessel connected to the gasification reactor by means of a duct. An advantage of the quenching vessel is that the design of such a vessel can be much simpler than a waste heat boiler having multiple heat exchanger banks. A further advantage is that a synthesis gas may be obtained which contains water at a level lower than the saturation content. This makes it possible to obtain a substantially cooled synthesis gas from which ash can be separated using a filter as for example described in EP-B-1178858 or by using a cyclone.
JP-A-53110967 describes a quenching vessel wherein a quenching medium is injected into a downwardly flowing gas under an angle.
Applicants have found however that the design of the vessel as shown in FIG. 4 of US-A-2006/0260191 or the design of JP-A-53110967 has certain disadvantages. A major concern regarding these designs is that ash, as one of the non-gaseous components as present in the synthesis gas, can form deposits on the vessel walls at downstream points relative to the position where water is injected.